Image Number 12 for United States Patent #5675331.
A decoding device is provided including a code FIFO memory unit for sequentially storing a bit stream, a barrel shifter for shifting and then outputting codes properly, an accumulator for computing the shift amount of the barrel shifter and issuing a request to read data to the code FIFO memory unit, a DCT coefficient decoder for decoding DCT coefficients, a variable-length code decoder for decoding variable-length codes other than DCT coefficients, a fixed-length code decoder for decoding fixed-length codes, a register unit for storing decoded data, a decoding controller for controlling the decoders in accordance with the decoded data stored in the register unit and decoded data output by the decoders and a memory controller for controlling operations to store DCT coefficients in a memory unit A. The DCT coefficient decoder, the variable-length code decoder and the fixed-length code decoder are connected in parallel to the output of the barrel shifter and the memory controller is controlled by the decoding controller. By virtue of this structure, the decoding device is capable decoding a bit stream comprising variable-length codes mixed with fixed-length codes. The decoding device is also capable of changing processing of a next code in accordance with decoded codes. Further, these operations can be implemented by means of a simple and reasonable configuration. On top of that, the process of decoding codes at a required high speed is carried out by an independent circuit, allowing the processing power of the decoding circuit to be enhanced.
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